Road-bed and process of making same.



UNITED STATES PATENT OFFICE.

BENJAMIN F. RICHARDSON, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO UNIONITE COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF DELAWARE.

ROAD-BED AND PROCESS OF MAKING SAME.

No Drawing.

To all whom it may concern:

Be it known that I, BENJAMIN F. RICH- ARDSON, a citizen of the United States, residing in Philadelphia, Pennsylvania, have invented certain Improvements in Road-Beds and Processes of Making Same, of which the following is a specification.

One object of my invention is to improve the construct-ion of a pavement having an asphalt Wearing surface, whereby the displacement of said wearing surface by the pushing or rolling action of the traflic is prevented. This object I attain by securing a top, or wearing, surface to the base by a binder whose adhesion cannot be broken from the base by the traflic.

A further object of the invention is to construct a pavement without the use of sand, or stone in either the binder or the wearing surface and to apply the binder and the surface material to the base while the material is either hot or cold.

A pavement constructed in accordance with my invention will have an increased efiiciency, as the constant action of the traffic has a tendency to improve the surface without destroying its adhesion to the base.

The present asphalt pavements having a binder of stone and asphalt and a surface of sand and asphalt are not efficient under heavy traffic, especially where large motor trucks are used, as the traffic has a tendency to push the surface, causing it to form waves, which makes the surface,.uneven.

In carrying out my invention, I first provide a concrete base consisting of cement, stone and stone grit in the general proportion of 1 of cement, 4 of stone, and 2 of .stone grit, but it will be understood that these proportions may be varied according to the voids in the concrete. In some instances, there may be a sub-concrete base of cement, stone and sand, but the base to which the surface material is attached is as above described.

In making the base, it is desirable to have the concrete as nearly voidless as possible. It should be thoroughly mixed and should also be of a proper thickness, for example from four to six inches, according to traflic requirements. The concrete should be thoroughly tamped until water flushes to the surface and then smoothed with a level board to line and grade.

Specification of Letters Patent.

Patented July 28, 1914.

Application filed December 31, 1913. Serial No. 809,743.

I coat the surface of the above base with a binder of refined bitumen dissolved in benzol after said surface has been cleansed. This binder may be applied with a pressure spray, or other suitable implement or machine, and care should be taken to coat the entire surface of the concrete base.

As hereinabove stated the binder is refined bitumen dissolved in benzol (C H which is a coal tar distillate having a specific gravity of from .8 to .9 and, preferably, not over 50 per cent. of benzol is used. The benzol can be poured onto the cold bitumen, which it usually takes twenty-four hours to dissolve, or it can be poured into the bitumen, which may be heated to about two hundred degrees Fahrenheit. Hot bitumen can be poured into the benzol and the same agitated. The hot methods are quicker, but not so economical as the cold method, due to the loss of benzol by evaporation. The binder should have a specific gravity of .94 when finished and ready for application. The binder so prepared is in an extremely thin condition, enough benzol having been added to insure the formation of a liquid body sufliciently fluid to enter the pores of the surface portion of the concrete and then, upon evaporation of the solvent, to leave a coating or thin layer of bitumen upon such surface to which the mastic coat or Wearsurface of rock asphalt, or rock asphalt and bitumen, will closely adhere. I find that when this binder is applied to a concrete base it adheres tenaciously thereto and when the top course is applied, it unites the same to the base in such a manner that it is impossible to remove the said top course or to cause it to creep or roll by the action of heavy traffic.

I find that benzol is a powerful solvent for bitumen and when a solution of bitumen in benzol is applied to the concrete surface, it grips the concrete with such tenacity as to be practically inseparable therefrom under severe traffic conditions.

The mastic top course, which is spread upon the binder, ranges from one-eighth to one-fourth of an inch in thickness, depen ing upon the climatic conditions, the 100a: tion of the pavement, and the traffic and it is made of rock asphalt and bitumen in about the proportion of 95 per cent. rock asphalt and 5 per cent. bitumen. This proportion may be varied according to the circumstances above described; the addition of the bitumen to the asphalt being to make the top course self-healing.

The bitumen and rock asphalt may be heated in the ordinary manner, but when the top course is applied then I dissolve the bitumen in benzol and add it to the rock asphalt. The bitumen may be used as a flux in a proportion to suit the atmosphere and the traffic. Rock asphalt is used to provide a wearing surface which will not wave under heavy traflic. The mastic top course is preferably applied at from four hundred to four hundred and fifty degrees Fahrenheit and is rolled in the usual manner with a heavy roller, preferably weighing from eight to ten tons. In the preparation of this mastic top course no sand or stone is used and the course is of such a consistency that if it breaks or cracks it will heal itself and will take up enough loose grit under the action of the traffic to counterbalance the wear.

While I have specifiedbenzol, it will be understood that itshomologues, toluol and xylol, may be used for dissolving the bitumen which forms the binder and in some instances instead of benzol carbon disulfid (CS may be used, though I prefer to use benzol as above described.

1. The process herein described of making a roadbed which consists in forming a concrete base of cement, stone and stone grit; applying thereto a binder consisting of bitumen dissolved in a light.hydrocarbon of the benzol series sufliciently fluid to carry the bitumen into the pores of the'concrete before the solvent body evaporates and to coat the concrete surface with a bituminous body upon evaporation; then applying mastic to form a wear-surface to said bituminous-surfaced concrete, and finally rolling said mastic.

2. The process herein described of making a roadbed which consists in forming a concrete base of cement, stone and stone grit; applying thereto a binderjconsisting of bitumen dissolved in benzol and sufiiciently fluid to carry the bitumen into. the-pores of the concrete before the benzol evaporates, and to coat the concrete surface with a bituminous body upon evaporation; then applying rock asphalt and bitumen free from sand to said bituminous-surfaced concrete to form a wear-surface, and finally rolling said mastic.

3. The process herein described of making a roadbed which consists in forming a smooth-surfaced concrete base in which sand is omitted; applying to said surface a thin solution of bitumen dissolved in a light hydrocarbon of the benzol group in which the proportions of solvent and bitumen are substantiall equal; said [solution being sufficiently uid to carry the bitumen into the pores of the concrete before evaporation of the solvent takes place and to leave upon evaporation a bituminous coating upon the surface of the concrete ready to receive a wear-surface of asphalt or equivalent material, then applying mastic to said bituminous-coated surface, and finally rolling said mastic.

4. The process herein described of making a roadbed which consists in forming a smooth-surfaced concrete base in which sand is omitted; applying to saidsurface a thin solution of bitumen dissolved in benzol in which the proportions of solvent and bitumen are substantially equal; said solution being sufficiently fluid to carry the bitumen into the pores of the concrete before evaporation of the solvent takes place and to leave upon evaporation a bituminous coating upon the surface of the concrete ready to receive a wear-surface of asphalt or equivalent material, then applying rock asphalt and bitumen to said bituminous-coated concrete surface to form a wear-surface, and finally rolling said wear-surface.

5. A pavement havingya base of, concrete made up of stone and cementin which the surface consists of stone, stone grit and cement, a binder consisting of bitumen in solution of one of the-light hydrocarbons applied to the surface of such concrete, said binder entering the pores of the concrete and leaving a bituminous body upon the surface of the same after evaporation, and a top course of rock asphalt with bitumen applied directly to said bitumen surfaced concrete, said top course being self-healing; the binder being free of stone or sand.

6. A pavement having a base of concrete made up of stone and cement in which the surface consists of stone, stone grit and cement, a binder consisting of bitumen in solution with benzol applied to the surface of such concrete; said binder being sufficiently fluid to enter the pores of the concrete before evaporation and to leave. a thin bituminous coating upon the surface of the concrete after evaporation, anda thin topcourse of rock asphalt. with bitumen added thereto to make such top course self-healing; the top course and binder being free of stone or sand.

7. A pavement having a base of concrete; a binder consisting of bitumen in solution with benzol applied to the surface of such concrete, said binder being sufficiently fluid to enter the pores of the concrete before evaporation and to leavea thin bituminous coating upon the surface of said concrete after evaporation; with a surface coating bound to the concrete base by said intermediate bituminous coatingi 8. A pavement having a base of concrete; a binder consisting of bitumen in solution with benzol applied to the surface of such concrete, said binder being suificiently fluid In testimony whereof, I have signed my to enter the pores of the concrete before name to this specification, in the presence of 10 evaporation and to leave a thin bituminous two subscribing witnesses.

coating upon the surface of said concrete BFNJAMIN F RICHARDSON after evaporation; with a surface coating J of rock asphalt and bitumen bound to the Witnesses:

concrete base by said intermediate bitu- CLYDE T. Mom, minous coating. WM. A. BARR. 

